The initial objective of the study is to carry out laboratory investigations using in vitro caries models to demonstrate whether salivary pellicle is a major inhibitor of caries. We will attempt to relate this inhibition to the presence of a specific protein or proteins in pellicle or saliva. The secondary objective is to examine saliva from caries-prone, caries-resistant, and geriatric subjects for the presence of specific proteins and to investigate these parameters as possible caries predictors. Such information may lead to improved caries-preventive measures or to enhanced prognostic procedures for patients with salivary gland malfunction. In order to achieve these objectives the specific aims are: (1) To use an in vitro caries model, and (2) an apatite dissolution model, to study the caries inhibitory effect of (a) whole saliva, (b) a previously identified salivary protein or proteins with molecular weight of about 12,000. High Performance Liquid Chromatography (HPLC) will be utilized to determine whether a specific protein or proteins are the inhibitory factors. (3) When 1 and 2 have been established, to investigate whether saliva from a range of subjects contains the specific proteins identified as caries inhibitors. These proteins will then be examined from these subjects in the caries in vitro model and the apatite dissolution model. (4) To collect saliva from subjects in the categories of caries-prone, caries-resistant, and a geriatric population with reduced salivary function, and to examine their saliva by HPLC. These subjects will be drawn from other proposals. Specific inhibitory protein presence (1 and 2 above) will be examined in relation to age and caries status. (5) To use the animal model to study these specific inhibitory proteins in relation to induced hyposalivation. (6) If a relationship is found between a specific protein or proteins and age or caries status, this concept will be developed as a caries diagnostic tool for caries-susceptible people. This study, together with other studies in the Proposed Rochester Cariology Center, will provide chemical and microbiological parameters for the improved diagnosis and treatment of caries susceptible subjects.